Stuck in a bootloop....HELP!!!!!

Last night I went from SS 4.9 to UD 2.1.0 and everything has been working great till about an hour ago. I changed system font and the phone shut down and started rebooting. When it gets to the Ultimate Droid screen it will light up the buttons and then vibrate like it is loading. It keeps doing this over and over. I tried pulling the battery and holding z when restarting but it will not go to recovery. It just goes back to the UD screen. What can I do?